This invention relates generally to electronic devices utilized in radar systems. Specifically, this invention relates to Doppler radars which utilize audio indicators in communicating information to human radar operators.
Existing Doppler radar target detectors provide an audio signal to a target detector operator as a means of communicating information about objects or targets illuminated by the radar. For example, the target detector may generate a tone which corresponds to the target. When the target approaches the target detector, the tone exhibits a pitch higher than the pitch of a reference tone. Conversely, when the target recedes from the target detector, the tone exhibits a lower pitch than that exhibited by the reference tone. Further, the greater the speed of the target toward or away from the target detector, the greater the difference in pitch between the target's tone and the reference tone. Accordingly, the target detector operator knows whether a target is approaching or receding and an approximate speed of the target by listening to the target's tone and the reference tone.
Additionally, such target detectors provide the target detector operator information useful in identifying the target. Information about the target's speed along with short time interval changes in the pitch and amplitude of the target's tone give the target detector operator an indication of the type of object which the target represents. For example, the target tone produced from a walking person may sound like a "whish" while the tone produced from a moving vehicle may sound like a "whirl."
Accordingly, a target detector operator confronts a large quantity of audio information in the process of operating the target detector. The audio stimulation is very demanding on the concentration of the operator. Perceptual saturation and fatigue may quickly occur. Resultingly, poor performance occurs in the operation of the target detector due to the demands placed upon the operator.
Additionally, such target detectors are susceptible to electronic jamming signals. With great demands placed on the operator's concentration, the operator is easily deceived by jamming signals which simulate valid radar reflections.